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AS568-429 O-Ring Size
400 series · 1/4" cross section · Industrial flanges and piping
Inside diameter × cross section
126.36 × 6.99 mm
4.975″ × 0.275″ ·
outside diameter 140.33 mm (5.525″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 4.975″ | 126.36 mm |
| Cross section (CS) | 0.275″ | 6.99 mm |
| Outside diameter (OD) | 5.525″ | 140.33 mm |
Outside diameter is not measured, it is derived: OD = ID + 2 × CS.
If your measured OD disagrees with this, trust the ID and cross section — measuring
across the outside of a flexible ring is the least reliable of the three.
If you measured a used one
A ring pulled out of service will measure smaller than 126.36 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -429 is very likely still the correct part. Ordering the size your worn ring measures is how the same failure repeats. More on this →
Nearby sizes in the 400 series
These share the same 1/4" cross section, so if the thickness is right but the diameter is off, your ring is probably one of these.
| Dash | ID (mm) | ID (in) | OD (mm) |
|---|---|---|---|
| -428 | 123.19 | 4.85″ | 137.16 |
| -430 | 129.54 | 5.1″ | 143.51 |
| -427 | 120.01 | 4.725″ | 133.98 |
| -431 | 132.71 | 5.225″ | 146.68 |